The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
Referring to FIGS. 1A and 1B, conventional cantilever probe elements are made from circular or round rod stock 100 that is then chemically etched or mechanically ground at a tip end to achieve a circular taper to reduce the size so that more probe elements may be adjacently aligned for finer pitch integrated circuit (IC) device testing. The probe elements are then bent to form a knee at a designed bend angle and bend radius.
The etched length, i.e., the portion of the probe element that is chemically etched, is the tip length (below the knee) and a designed portion of the beam length above the knee. Most conventional chemically etched probe elements have an etched length that does not include the entire beam length.
Mechanically grinding or chemically etching probe elements is time consuming and expensive. Furthermore, diameter 102 of the ground or chemically etched round conventional cantilever probe elements is not practical for a probe card pitch finer than about 40 μm in fine pitch applications. Otherwise, the crowded adjacent probe elements may electrically short, causing the probe card to be ineffective and/or unreliable.
Such conventional cantilever probe elements are generally made from tungsten (W), tungsten-rhenium (WRe), beryllium-copper (BeCu) or Paliney® 7, a precious-metal alloy comprised of gold, palladium, platinum, silver, copper and zinc (Paliney® is a registered trademark of the J. M. Ney Company, Ney Industrial Park, 2 Douglass Street, Bloomfield, Conn. 06002).
Softer materials may be desirable to use for these probe elements; however, grinding such softer materials tends to cause unacceptable curling or fish-hooking of the tips. Also such softer materials typically would utilize probe element wires having even larger diameters to achieve acceptable rigidity, performance and robustness which would even further restrict the probe card pitch that could be achieved.
The “Probe Card Tutorial” by Otto Weeden, Senior Applications Engineer, Keithley Instruments, Inc., © 2003, Keithley Instruments, Inc. describes issues related to parametric testing of epoxy and blade probe cards. It discusses the effect of probe wire diameter vis-à-vis contact force and pad pitch.
Thus, it would be desirable to provide a method and apparatus for providing cantilever probe cards having finer pitch and/or comprised of cantilever probe elements comprised of more favorable materials overcoming certain of the deficiencies related to conventional techniques.